The calcite crystals contain traces of ancient microbial activity. Credit: Henrik Drake
A new study reveals that microbial life deep within Earth has persisted and repeatedly flourished through hundreds of millions of years of mountain-building and erosion. By analyzing minerals, fluids and gases from a 2.3-kilometer-deep (1.4-mile-deep) borehole in central Sweden, researchers have uncovered episodic bursts of methane-producing life linked to major geological events that shaped Scandinavia. The paper is published in the journal Communications Earth & Environment.
The deep continental subsurface is one of Earth's least explored ecosystems. Yet it hosts microbial communities capable of ancient metabolisms such as methanogenesis—the production of methane by microorganisms. Now, an international research team led by scientists at Linnaeus University has reconstructed an unprecedented long-term history of these deep biosphere processes.
Methane signatures locked in stone
The researchers analyzed fracture-filling calcite minerals from the COSC‑2 drill core, drilled west of Östersund in central Sweden. The borehole extends more than 2,300 meters (1.4 miles) into the bedrock and passes through several geological layers formed at different times in Earth's history.
